User interface devices for data entry and graphical user interface pointing have been known for many years. The most common devices include the computer mouse (usually attributed to English, Engelbart, and Berman “Display-Selection Techniques for Text Manipulation, IEEE Transactions on Human Factors in Electronics, pp. 5-15, vol. HFE-8, No. 1, March 1967), the trackball, the touchpad in both finger-operated (for example, the various finger-operated devices produced by Symantec Corp., of Springfield, Oreg.) and stylus-operated (for example, products used with desktop workstation computers—Wacom Technology Corp., of Vancouver, Wash.) versions, and display-overlay touchscreens. Other historical and exotic devices include various types of light pens and the Data Glove™ (produced by VPL Research, Inc., of Redwood City, Calif.).
Most user interface devices for data entry and graphical user interface pointing commonly used with computers or with equipment providing computer-like user interfaces have two wide-range parameter adjustment capabilities that are usually assigned to the task of positioning a screen cursor within a two-dimensional display. In many cases, one, two, or three binary-valued “discrete-event” controls are provided, typically in the form of spring-loaded push-buttons.
More recently, computer mice have emerged that provide an additional “scroll” finger-wheel adjustment (for example, between two control buttons) to provide a third wide-range parameter adjustment capability (for example, various products developed by Logitech Inc., of Fremont, Calif.). A mouse of this configuration is often referred to as a “Scroll Mouse” since this third wide-range parameter is typically assigned the task of positioning a vertical scroll bar in an actively selected window. This additional finger-wheel adjustment may also operate as a spring-loaded push-button, thus providing an additional binary-valued “discrete-event” control. Typically this additional binary-valued “discrete-event” control is used to turn on and off an automatic scrolling feature which controls the rate and direction of automatic scrolling according to vertical displacement of the displayed cursor.